Prediction of Post-Yield Performance of Hybrid Precast Beams Based on Strength Degradation

In this study, the post-yield load-displacement relationships of precast composite beams with various boundary conditions were predicted based on strength degradation data. The aim of this study was to explore the post-yield hysteretic structural behavior of precast composite concrete beams based on stiffness degradation, which was calculated by normalizing effective stiffness with respect to stiffness at the yield limit state. The influence of degradation of the effective stiffness on the post-yield behavior of the specimens was investigated with extensive test data gathered using gauge measurements. The hysteresis behavior, determined from cyclic tests of full-scale composite specimens under the various boundary conditions, was used to predict the post-yield deflection of the composite beams. This paper collected post-yield test data for 13 specimens, including five pre-stressed specimens, to investigate the influence of pre-stressing forces on the post-yield characteristics of steel-concrete composite beams. The prediction of post-yield load-displacement relationships of the composite beams was based on six steps and matched well with test data, verifying the proposed analytical procedures for estimating post-yield performance. The post-yield load-displacement relationships of precast composite concrete beams were satisfactorily predicted by the simplified but convenient method.